What does Windows error code 378 (ERROR_CLOUD_FILE_ALREADY_CONNECTED) mean?

 
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ERROR_CLOUD_FILE_NOT_IN_SYNC ERROR_CLOUD_FILE_NOT_SUPPORTED

ERROR_CLOUD_FILE_ALREADY_CONNECTED

Only one active CFAPI connection can own a sync-root path

ERROR_CLOUD_FILE_ALREADY_CONNECTED occurs when a provider attempts to connect a sync root that already has an active communication channel. CfConnectSyncRoot permits at most one connection for a given path, although one provider process may connect to multiple different roots and receive a distinct connection key for each.

Check for duplicate provider instances, service and tray processes starting the same account, or a reconnect path that runs before the prior connection is disconnected. Log the process ID, sync-root path, and returned connection key. Do not solve this by registering a second provider identity over the same directory; coordinate instance ownership and use CfDisconnectSyncRoot during orderly shutdown or account switching.

What to inspect

  • Search for multiple provider processes connected to the same user and root.
  • Store connection keys per root and protect connect/disconnect with process-level synchronization.
  • Verify shutdown waits for the intended disconnect path before reconnecting.

References


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